Submaximal Test Research Articles

Effects of Different Durations at Fixed Intensity Exercise on Internal Load and Recovery-A Feasibility Pilot Study on Duration as an Independent Variable for Exercise Prescription.

Duration is a rarely investigated marker of exercise prescription. The aim of this study was to test the feasibility of the methodological approach, assessing effects of different duration constant-load exercise (CLE) on physiological responses (internal load) and recovery kinetics. Seven subjects performed an incremental exercise (IE) test, one maximal duration CLE at 77.6 ± 4.8% , and CLE’s at 20%, 40%, and 70% of maximum duration. Heart rate (HR), blood lactate (La), and glucose (Glu) concentrations were measured. Before, 4, 24, and 48 h after CLE’s, submaximal IE tests were performed. HR variability (HRV) was assessed in orthostatic tests (OT). Rating of perceived exertion (RPE) was obtained during all tests. CLE’s were performed at 182 ± 27 W. HRpeak, Lapeak, , and RPEpeak were significantly higher in CLE’s with longer duration. No significant differences were found between CLE’s for recovery kinetics for HR, La, and Glu in the submaximal IE and for HRV or OT. Despite no significant differences, recovery kinetics were found as expected, indicating the feasibility of the applied methods. Maximum tests and recovery tests closer to CLE’s termination are suggested to better display recovery kinetics. These findings are a first step to prescription of exercise by both intensity and duration on an individual basis.

Normative reference values and regression equations to predict the 6-minute walk distance in the Asian adult population aged 21-80 years.

The 6-min walk test (6MWT) is a widely used field walking test. This study reports the normative reference values (NRV) of distance walked during 6MWT (6MWD) in healthy Singaporeans (aged 21-80) and updates the 6MWD reference equations. This information may facilitate the interpretation of the 6MWD in clinical populations. The Singapore Institute of Technology-Institutional Review Board (SIT-IRB Project Number: 2019099) approved this study to be carried out from June 2019 to January 2021. All participants gave written informed consent before data collection began. The six-minute walk test (6MWT) is a widely adopted submaximal field-walking test to evaluate functional exercise capacity. This validated test is a reliable, safe, inexpensive, and straightforward assessment tool commonly used as an outcome measure, using the distance walked (6MWD) as the primary outcome. An earlier study has established the normative reference values (NRV) and equation in healthy Singaporeans - however, the small sample size and narrow age range curb adequate representation of the adult population profile. This study aims to update the NRV and reference equations to predict the distance walked during 6MWT (6MWD) for healthy Singaporeans aged 21-80. This cross-sectional study recruited community-dwelling healthy subjects aged 21-80 via convenience sampling. Each subject completed two trials of 6MWT according to the standard protocol. Primary outcome measures included 6MWD, pre-and post-test heart rate (HR), oxygen saturation, and blood pressure (BP). 172 healthy Singaporeans (, ) participated. The overall mean 6MWD was metres. The age-stratified mean 6MWD ranged from metres (aged 21-39) to metres (aged 60-80). Age, gender, and percentage maximum HR predicted (%PredHRmax) were the most significant variables (). 6MWD reference (HR reserve, bpm) (weight, kg), . Applying equations from other studies to the Singaporean population resulted in an overestimation of the 6MWD. This study updated the NRV and reference equations of 6MWD for healthy Singaporeans aged between 21-80 years. This update revises the local benchmarks of 6MWD in Singapore, a widely adopted outcome measure.

Evaluation of a Treadmill-Based Submaximal Fitness Test in Pugs, and Collecting Breed-Specific Information on Brachycephalic Obstructive Airway Syndrome.

Simple SummaryIn the present study, a submaximal fitness test on a treadmill was evaluated to assess its feasibility under standardised conditions. Moreover, its effectiveness in identifying pugs with clinical signs of brachycephalic obstructive airway syndrome was examined. It was apparent that respiratory symptoms can be exposed during the fitness test, and intensified with an increased duration of exercise. This method of testing improves the clinical evaluation of the dogs and helps identify restrictions due to brachycephalic obstructive airway syndrome. Since most of the dogs could be familiarised with the treadmill, it may be a feasible option for performing fitness tests in brachycephalic dogs. Major benefits, therefore, are that each dog can be closely monitored during the entire process, and that the examination can be conducted under standardised conditions.Despite efforts of veterinarians and breeders, brachycephalic obstructive airway syndrome (BOAS) is still a common problem in pugs, underlining the need for objective tests to identify and prevent breeding with affected dogs. In the current study, a submaximal, treadmill-based fitness test was evaluated as a tool to identify signs of airway obstruction not recognisable under rest conditions. In addition to this, different body conformation and measurements were assessed regarding their association with BOAS. A total of 62 pugs and 10 mesocephalic dogs trotted with an individual comfort speed on a treadmill for 15 min. Before and during the examination, dogs were examined for signs of respiratory distress, and a functional BOAS grading was applied. The influence of body conformation on BOAS grading was tested in a univariable and multivariable logistic regression model. During exercise, more respiratory noises were observed, and existing respiratory noises became more apparent in comparison to when at rest. In the multivariable logistic regression model, no factor had a statistically significant influence on BOAS classification. Submaximal fitness testing helped to identify signs of respiratory distress not apparent under resting conditions, and could be a valuable addition for identifying dogs with BOAS. Performing testing on a treadmill facilitates continuous observation of the patients, and enables standardisation of the test regarding the test environment, as well as provides an uninterrupted, steady workload.

Prognostic value of 6-min walk test compared to cardiopulmonary exercise test in patients with severe heart failure.

The 6-min walk test (6MWT) and cardiopulmonary exercise test (CPET) are both predictive in heart failure (HFrEF). Although 6MWT substitutes for CPET in HFrEF patients, as submaximal testing may be preferable, its prognostic superiority still needs to be verified, particularly in regard to beta blockers (BBs). We aimed to compare the prognostic role of CPET and 6MWT and investigate whether BB therapy influences the predictive value. This is a single-center, retrospective study. Advanced HFrEF patients were followed up for 3 years: events were cardiovascular death or urgent heart transplantation. We analyzed the predictive capacity of CPET and 6MWT in patients, and subdivided according to use of BBs. In a group of 251 HFrEF patients, we found a correlation between meters and peak VO2 (r2 = 0.94). Over the 3-year follow-up, 74 events were recorded. Both CPET and 6MWT variables were correlated with outcome at univariate analysis (meter and VE/VCO2 slope, peak VO2, VO2 at ventilatory anaerobic threshold, percentage predicted of peak VO2), but only percentage predicted of peak VO2 (pppVO2) was an independent predictor. In 103 HFrEF patients on BBs (23 nonsurvivors), neither pppVO2 nor meter were predictive, while in 148 patients not treated with BB (51 with events) pppVO2 was selected as an independent prognostic parameter (P = 0.001). 6MWT is a valid alternative to CPET, although the percentage of predicted of peak VO2 emerged as the strongest predictor. Nonetheless, our results suggest that both functional derived parameters are not predictive among those patients treated with BBs. Further studies are necessary to confirm these findings.

ADHERENCE TO PHYSICAL ACTIVITY IN OLDER ADULTS WITH HYPERTENSION: LESSONS FROM THE HOLDAGE RANDOMIZED CONTROLLED TRIAL

Objective: Isometric exercise training (IHT) may be a practical, inexpensive and time efficient modality to reduce blood pressure (BP). We report preliminary exercise adherence data from HoldAge (NCT04275037) among older adults with high-normal BP to stage I hypertension. Design and method: Participants performed a total of 24 sessions of IHT or aerobic exercise training (AET), 3 times/week, for 8 wks. IHT was 4x45 min contractions, alternatively with both hands, at an intensity of 50% of the maximum voluntary contraction, with 1 min rest between sets. AET was walking 20–30 min at an intensity of 50–70% of the estimated peak maximal oxygen consumption (VO2peak) assessed with a submaximal step test. The attention control (AC) group received standardized optimal medical care including lifestyle advice. The adherence to IHT was a mean quality score recorded in the digital dynamometer, representing the % time participants performed the exercise sessions at the prescribed intensity. The adherence to AET was the time spent exercising at the prescribed intensity, recorded with a heart rate monitor. Results: 95 eligible people were contacted to participate and 72 agreed to participate (76%). Of these, 49 participants have finished the study (IHT:19; AET:18; AC:12) with 4 dropouts (AET:1; AC:3). Three participants changed their antihypertensive medication and were excluded (AET:1; AC:2). IHT had a self-reported exercise adherence of 96.7 ± 9.3%, while data downloaded from the exercise devices showed an adherence of 88.6 ± 13.9% of the sessions, with 2.3 ± 3.3% incomplete sessions. IHT registered a mean quality score of 91.8 ± 11.2% for the right hand (mean strength: 22.6 ± 7.7 kg), 91.7 ± 13.5% for the left-hand (mean strength: 20.9 ± 8.6 kg), and 91.6 ± 12.2% for both hands. AET had a self-reported exercise adherence of 83.8 ± 33.6%, consistent with the data downloaded from the heart rate monitors. AET participants spent a total of 578.1 ± 263.6 min exercising, of which 153.3 ± 152.4 min (22.6 ± 23.2%) was spent walking at the prescribed intensity, 286.3 ± 210.5 min (45.4 ± 35.2%) was below and 137.8 ± 154.7 minutes (19.4 ± 21.7%) was above. Conclusions: Exercise adherence in HoldAge is high in both IHT and AET, but the time spent at the prescribed intensity appears to be higher in IHT than AET.

Development of a functional assessment task in metastatic breast cancer patients: the 30-second lie-to-sit test

Purpose To develop a physical function test based on lie-to-sit transition and to study its feasibility in patients suffering from metastatic breast cancer (MBC). Materials and methods This cross-sectional study recruited 90 women diagnosed with MBC. Patients were asked to transfer from lying to sitting position as fast as possible during 30 s, performing the 30-second lie-to-sit test (30-LTS). Heart rate (HR), rate of perceived exertion (RPE) and number of repetitions were measured. An assessment included the 30-second sit-to-stand test (30-STS), handgrip strength, Upper Limb Functional Index (ULFI) and Lower Limb Functional Index (LLFI). Pearson correlation was calculated between 30-LTS and independent outcomes. A linear regression model explaining the 30-LTS results was further constructed with variables that had a significant correlation. Results About 72 patients were measured, of which 65 were able to perform 30-LTS. Subjects performed 8.13 repetitions on average, with a mean RPE of 4.78 (0–10), reaching 63.08% of maximal HR. 30-LTS was significantly correlated with 30-STS (r = 0.567), handgrip (p = 0.26) and LLFI (r = 0.348). The regression model was significant (F = 4.742; p = 0.00), and these variables explained 32% of the variance of the 30-LTS. Conclusion The 30-LTS showed to be a feasible functional and submaximal test in a sample of MBC. IMPLICATIONS FOR REHABILITATION The 30-second lie-to-sit (30-LTS) developed does not require the patient to acquire a standing position and therefore it is an alternative to other more biomechanically demanding tests such as a 30 second sit-to-stand test or Timed up-and-go. 30-LTS involves both a functional and energy system assessment tool that can be implemented by allied health professionals in oncology rehabilitation to individualize exercise prescription, as well as for functional screening purposes. The present study adds value to current research focused on individualizing exercise prescription in the oncology field and provides reference values of function in metastatic breast cancer patients.

Modelling 5-km Running Performance on Level and Hilly Terrains in Recreational Runners.

Simple SummaryIn the last decades, performance models have helped to comprehend the mechanisms involved in long-term physical performance. In addition, predictive models have aided in the evaluation and prescription of physical training. Here, we tested the hypothesis that physiological assessments under inclined conditions would better explain hilly running performance. We also checked the predictive role of running biomechanical, anthropometric, and neuromuscular factors. Velocity associated with maximal oxygen consumption was more predictive when assessed in inclined conditions (7%) than testing at level. Secondarily, ventilatory thresholds submaximal heart rate improved the performance models at hilly and level conditions. Spatiotemporal, strength, and anthropometric factors were not determinants of performance. Physiological assessments in inclined conditions predict 5-km running performance at hilly terrains in higher degree than evaluations at level in endurance runners.Incline and level running on treadmills have been extensively studied due to their different cardiorespiratory and biomechanical acute responses. However, there are no studies examining the performance determinants of outdoor running on hilly terrains. We aimed to investigate the influence of anthropometrics, muscle strength, and cardiorespiratory and gait spatiotemporal parameters during level (0%) and inclined (+7%) running on performance in level and hilly 5-km races. Twenty male recreational runners completed two 5-km outdoor running tests (0% vs. +7% and −7%), and two submaximal (10 km·h−1) and incremental treadmill tests at 0 and 7% slopes, after complete laboratory evaluations. The velocity at maximal oxygen consumption (VO2max) evaluated at 7% incline and level treadmill running were the best performance predictors under both hilly (R2 = 0.72; p < 0.05) and level (R2 = 0.85; p < 0.01) conditions, respectively. Inclusion of ventilatory and submaximal heart rate data improved the predictive models up to 100%. Conversely, none of the parameters evaluated in one condition contributed to the other condition. The spatiotemporal parameters and the runners’ strength levels were not associated to outdoor performances. These results indicate that the vVO2max evaluated at similar slopes in the lab can be used to predict 5-km running performances on both level and hilly terrains.

Submaximal Walking Tests: A Review of Clinical Use

ABSTRACT Though graded exercise testing is the gold standard for assessing cardiorespiratory fitness, submaximal exercise testing is also useful to assess cardiorespiratory status and functional capacity when maximal testing is not feasible. Submaximal walking tests are advantageous as they have less risk, lower cost, require less time and equipment, and walking is a familiar activity that is easy to do in most environments. A number of submaximal walking tests exist for both overground and treadmill walking. Regression equations to predict V̇o2max values based on walking time, distance, and other variables that influence exercise tolerance have been developed for some submaximal tests, including the Rockport Fitness Walking Test and the Single-Stage Treadmill Walk Test. The 6-Minute Walk Test is a common test used in clinical populations to predict prognosis and assess change in functional capacity after intervention. Determining which submaximal walking test to use depends on purpose and setting, subject characteristics, equipment availability, space, and time. This review will provide clinicians with an overview of submaximal walking test protocols and provide reference equations and minimal clinically important difference values to interpret results.

Neuromuscular Training, Exercise Physiology Clinic, Real-time Exercise, and Cardiac Rehabilitation

Neuromuscular Training, Exercise Physiology Clinic, Real-time Exercise, and Cardiac Rehabilitation

C71 USE OF THE 6–MINUTE WALKING TEST (6–MWT) AS AN ALTERNATIVE TO INCREMENTAL ERGOMETRIC TESTING FOR THERAPEUTIC EXERCISE PRESCRIPTION IN CARDIOLOGICAL REHABILITATION

Abstract According to the guide lines and statements from scientific societies, the determination of exercise intensity at the beginning of a cardiac rehabilitation (CR) program should include a cardiopulmonary test as the optimal standard and an incremental “symptom–limited” ergometric test (ET) as the minimal standard. However, the preliminary ergometric evaluation is often not done, because of patient’s (pt) inhability to perform ET, temporary contraindications to ET or difficulties related to organization. Therefore, we assessed whether it is possible to set an effective and safe work intensity for each pt, using a submaximal test such as the 6–MWT, Methods Thirty pts (20 M and 10 F; mean age 61 ± 10.1 yr) consecutively referred to an outpatient CR after cardiac surgery (15 pts) or acute coronary syndrome (15 pts) were enrolled. Eligible pts after assessment of balance and gait with the Tinetti scale (score ≥ 19), performed both a 6MWT and a ET on the cycle ergometer within one week of enrollment. By t–test for paired data, watts at ET peak (W peak) were compared with W peak calculated by the two formulas of Hill and that of Luxton using anthropometric data and the result of the 6–MWT (Holland AE et al. Estimating peak work rate during incremental cycle ergometry from the 6–minute walk distance: differences between reference equations. Respiration 2011;81:124–128). In addition, we tested whether the maximum heart rate (max HR) achieved at 6–MWT falls within the training frequency calculated using the Karvonen formula (THR). Results There is a statistically significant difference between W peak and W peak calculated with the Hill formulas (p &amp;lt; 0.0001). On the contrary, the difference is not significant applying the Luxton formula (p = 0.7). The maximum HR values reached at 6–MWT fell within the THR in 63% of cases (confidence intervals 0.46–0.80). Conclusions At the moment, we do not have reliable formulas for calculating the workload from a submaximal test in the population of cardiac patients. The Luxton formula deserves to be evaluated on a larger sample. Finally, the max HR at 6–MWT is a good and sufficiently safe parameter for programming an initial therapeutic exercise as it falls within the THR in the most cases and even when it does not, the difference is only a few beats.

Cardiorespiratory fitness, genetic susceptibility, inflammation and risk of incident type 2 diabetes: A population-based longitudinal study

ObjectiveTo examine whether the association between cardiorespiratory fitness (CRF) and type 2 diabetes (T2D) is modified by genetic susceptibility and inflammation. ParticipantsThe prospective study included 57,185 participants (40–70 years) who were free from T2D and received the CRF assessment at enrollment (2006–2010) in the UK biobank. CRF was examined through a submaximal cycle ergometer test and expressed in metabolic equivalent of tasks (METs), genetic susceptibility was quantified using a genetic risk score, and inflammation was assessed according to the concentration of C-reactive protein. All these three factors were categorized into tertiles. ResultsDuring a median follow-up of 10.4 years, 5477 (7.0%) cases of T2D were ascertained. CRF was inversely associated with the risk of T2D in a dose-response manner. The hazard ratio (HR) was 0.85 (95% confidence interval [CI]: 0.79–0.92) per 1 MET increment of CRF. There was a significant interaction between CRF and genetic susceptibility to T2D in relation to the risk of T2D (P for interaction = 0.03). Compared with participants with high CRF and low genetic susceptibility, the HR was 4.98 (95% CI: 3.17–7.82) for those with low CRF and high genetic susceptibility. A similar pattern was observed in participants with low CRF and high inflammation compared with those who had high CRF and low inflammation (HR = 2.53; 95% CI: 1.83–3.48), though the interaction between CRF and inflammation did not reach statistical significance. T2D risk declined progressively with increased CRF among different inflammation categories. ConclusionOur study reveals that genetic susceptibility may modify the association between CRF and T2D, highlighting that risk of T2D associated with genetics could benefit most from interventions on improving CRF.

Identifying new genetic markers for maximal oxygen uptake

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Central Norway Regional Health AuthorityNorwegian Health Association Introduction Cardiovascular disease (CVD) is the leading cause of death worldwide. Several studies have shown that low cardiorespiratory fitness (CRF) is a major risk factor for CVD. Low CRF is suggested to be a stronger predictor of CVD morbidity and mortality than established cardiovascular risk factors like obesity, diabetes, and cholesterol. Several studies suggest that CRF quantified as maximal oxygen uptake (VO2max) has a strong genetic component, estimated to be ~50%. Unfortunately, current studies on genetic markers for CRF are limited by small sample sizes. In addition, there are few studies on directly measured VO2max, as most of the previous studies are based on estimated CRF. Directly measured VO2max is considered as the gold standard for measuring CRF. Thus, a large-scale systematic screening for genetic variants associated with VO2max may provide awaited insight to this complex trait and discover possible links between VO2max and CVD. Purpose To identify and validate genetic factors associated with VO2max. Methods The genotypes of 70.000 participants from the Trøndelag Health study (HUNT) were imputed providing information on 25 million SNPs. We conducted a genome-wide association study (GWAS) including 4525 participants with directly measured VO2max from the HUNT3 Fitness study. The GWAS was performed using BOLT-LMM, adjusted for age, gender, physical activity, principal components, and genotyping batch. In addition, we ran a GWAS with the same covariates except physical activity. Further, gender specific analyses were conducted. For validation, similar analyses were performed in the United Kingdom Biobank (UKBB). In the UKBB, CRF was assessed through a submaximal bicycle test. The analyses of UKBB included ~60.000 participants and over 90 million SNPs. Results Two GWAS-significant (p &amp;lt; 5x10-8) SNPs associated with VO2max were identified in the total population in HUNT. Further, 24 GWAS-significant SNPs associated with VO2max in females, and two GWAS-significant SNPs associated with VO2max in males were discovered. Two of the 24 SNPs found in the female population were nominally significant in the UKBB. The validated SNPs are rs376927175, an intergenic SNP downstream of APBA1, and rs551942830 (proxy for rs190675254 with LD = 1.0), a 3 Prime UTR variant inside PIK3R5. PIK3R5 encodes the regulatory subunit of one class of PI3Ks, that is shown to be of importance in cardiac function and CVD. None of the SNPs found in the total population nor the male population were validated in UKBB. Conclusions We have identified 28 novel SNPs associated with VO2max in the HUNT cohort. Two of these SNPs were nominally validated in females in UKBB. One of the validated SNPs resides within a gene previously reported to be related to heart function and CVD. Further functional analyses using bioinformatic approaches may provide more information on the physiological importance of these findings and their relation to CVD.

The effect of different aero handlebar positions on aerodynamic and gas exchange variables

Adopting the time trial position (TTP) represents a notable improvement for cycling aerodynamic performance. Aero handlebars are designed to enable the cyclist to adopt a more aerodynamic TTP. However, it is unclear to what realistic extent the aero handlebar configuration affects the aerodynamics and physiological functioning. Thus this study aimed to investigate the effect of aero handlebar alterations on gas exchange parameters and aerodynamics of TTP. Seven male competitive cyclists and triathletes performed submaximal tests on a cycle ergometer at six different TTPs. Oxygen uptake, respiratory exchange ratio, minute ventilation and tidal volume were collected. Using the computational fluid dynamics (CFD) method, the detailed airflow patterns around the cyclist were investigated. The results were analyzed in terms of drag area, velocity and pressure distributions around the cyclist, surface pressure coefficient and wall shear stress magnitude. It was revealed that varying the aero handlebar position significantly influences aerodynamic performance, while maximal values of all the gas exchange variables remained unchanged. Compared to the cyclist’s preferred TTP, the frontal area, drag coefficient and drag area were reduced by 4.1%, 4.6% and 8.5%, respectively, when lowering the handlebar position by 5 cm, which overcomes the metabolic costs.

W243 Changes of erythrocyte metabolism in response to the [ARing]strand submaximal test in elite athletes

W243 Changes of erythrocyte metabolism in response to the [ARing]strand submaximal test in elite athletes

Maximal aerobic capacity is associated with lifting capacity, but not with self-reported functioning measures in patients with primary chronic low back pain: a cross-sectional study

ObjectiveMaximal exercise testing is considered the gold standard to assess V̇O2max. However, maximal exercise testing was previously deemed unfeasible and unsafe in chronic low back pain (CLBP) patients. Consequently, most...

Genome-Wide Association Study Identifies New Genetic Determinants of Cardiorespiratory Fitness: The Trøndelag Health Study.

Low cardiorespiratory fitness (CRF) is a major risk factor for cardiovascular disease (CVD) and a stronger predictor of CVD morbidity and mortality than established risk factors. The genetic component of CRF, quantified as peak oxygen uptake (V̇O 2peak ), is estimated to be ~60%. Unfortunately, current studies on genetic markers for CRF have been limited by small sample sizes and using estimated CRF. To overcome these limitations, we performed a large-scale systematic screening for genetic variants associated with V̇O 2peak . A genome-wide association study was performed with BOLT-LMM including directly measured V̇O 2peak from 4525 participants in the HUNT3 Fitness study and 14 million single-nucleotide polymorphisms (SNP). For validation, similar analyses were performed in the United Kingdom Biobank (UKB), where CRF was assessed through a submaximal bicycle test, including ~60,000 participants and ~60 million SNP. Functional mapping and annotation of the genome-wide association study results was conducted using FUMA. In HUNT, two genome-wide significant SNP associated with V̇O 2peak were identified in the total population, two in males, and 35 in females. Two SNP in the female population showed nominally significant association in the UKB. One of the replicated SNP is located in PIK3R5 , shown to be of importance for cardiac function and CVD. Bioinformatic analyses of the total and male population revealed candidate SNP in PPP3CA , previously associated with CRF. We identified 38 novel SNP associated with V̇O 2peak in HUNT. Two SNP were nominally replicated in UKB. Several interesting genes emerged from the functional analyses, among them one previously reported to be associated with CVD and another with CRF.

A lab-based comparison of differential ratings of perceived exertion between a run and jump protocol involving low or high impacts on the lower extremities

ABSTRACT The rating of perceived exertion method (RPE) allows to describe training intensity in a single value. To better understand the underlying components, the separate rating of perceived breathlessness (RPE-B) and leg-muscle exertion (RPE-L) has been proposed. Here we hypothesised that the separation between the two components may (partly) be determined by the impacts on the lower extremities. In this study, we aimed to experimentally evaluate the differential effect of high versus low impact running and jumping on RPE-B and RPE-L in team sport activities by manipulating the movement strategy (heel strike and passive landing pattern versus forefoot strike and active landing pattern). Eighteen recreational team sport players participated in two submaximal tests consisting of a sequence of running and jumping bouts, whilst ground reaction forces (GRF) were collected. RPE-B and RPE-L data were collected after each bout using the CR100 scale. Paired-samples t-tests were used to analyse between-session differences in these variables. GRF analysis showed that absorption mechanics differed considerably between the two sessions. RPE-L was on average 6.50 AU higher in the low impact session (p = 0.006). However, RPE-B was also increased by 4.96 AU with low impact (p = 0.009). We conclude that the extent to which the lower extremities are being exposed to high or low impacts does not explain a possible separation between the two RPE types. Highlights The separate rating of the different underlying components of RPE (e.g. variables related to the cardiorespiratory and the muscular system) may provide more insight in the relationship between training load and training outcomes, which likely differs between these components. The findings of this study do not support the idea that the separation in rating between perceived breathlessness (RPE-B, cardiorespiratory) and leg-muscle exertion (RPE-L, muscular) is also rooted in the extent to which musculoskeletal structures in the lower extremities are being exposed to high or low impacts.

Effect of a High Fat Diet vs. High Carbohydrate Diets With Different Glycemic Indices on Metabolic Parameters in Male Endurance Athletes: A Pilot Trial.

Consuming low glycemic carbohydrates leads to an increased muscle fat utilization and preservation of intramuscular glycogen, which is associated with improved flexibility to metabolize either carbohydrates or fats during endurance exercise. The purpose of this trial was to investigate the effect of a 4-week high fat low carbohydrate (HFLC-G: ≥65% high glycemic carbohydrates per day; n = 9) vs. high carbohydrate low glycemic (LGI-G: ≥65% low glycemic carbohydrates daily; n = 10) or high glycemic (HGI-G: ≥65% fat, ≤ 50 g carbohydrates daily; n = 9) diet on fat and carbohydrate metabolism at rest and during exercise in 28 male athletes. Changes in metabolic parameters under resting conditions and during cycle ergometry (submaximal and with incremental workload) from pre- to post-intervention were determined by lactate diagnostics and measurements of the respiratory exchange ratio (RER). Additionally, body composition and perceptual responses to the diets [visual analog scale (VAS)] were measured. A significance level of α = 0.05 was considered. HFLC-G was associated with markedly decreased lactate concentrations during the submaximal (−0.553 ± 0.783 mmol/l, p = 0.067) and incremental cycle test [−5.00 ± 5.71 (mmol/l) × min; p = 0.030] and reduced RER values at rest (−0.058 ± 0.108; p = 0.146) during the submaximal (−0.078 ± 0.046; p = 0.001) and incremental cycle test (−1.64 ± 0.700 RER × minutes; p < 0.001). In the HFLC-G, fat mass (p < 0.001) decreased. In LGI-G lactate, concentrations decreased in the incremental cycle test [−6.56 ± 6.65 (mmol/l) × min; p = 0.012]. In the LGI-G, fat mass (p < 0.01) and VAS values decreased, indicating improved levels of gastrointestinal conditions and perception of effort during training. The main findings in the HGI-G were increased RER (0.047 ± 0.076; p = 0.117) and lactate concentrations (0.170 ± 0.206 mmol/l, p = 0.038) at rest. Although the impact on fat oxidation in the LGI-G was not as pronounced as following the HFLC diet, the adaptations in the LGI-G were consistent with an improved metabolic flexibility and additional benefits regarding exercise performance in male athletes.

The safety and feasibility of early cardiorespiratory fitness testing after stroke.

Cardiorespiratory fitness testing is recommended as part of a pre-exercise evaluation to aid the programming of safe, tailored cardiorespiratory fitness training after stroke. But there is limited evidence for its safety and feasibility in people with stroke with varying impairment levels in the early subacute phase of stroke recovery. To assess the safety and feasibility of cardiorespiratory fitness testing in the early subacute phase after stroke. A sub-study of a larger single service, multi-site, prospective cohort feasibility study (Cardiac Rehabilitation in Stroke Survivors to Improve Survivorship [CRiSSIS]). Private subacute inpatient rehabilitation facilities. Consecutive admissions of people with ischemic stroke admitted to subacute rehabilitation facilities. Not applicable. Safety was determined by the occurrence of adverse or serious adverse events. Feasibility was determined by assessing the (1) number of participants recruited and (2) number of participants able to complete the fitness test. Between April 2018 and December 2019, a total of 165 people with stroke were screened to participate; 109 were eligible and 65 were recruited. Of the 62 who completed testing, 41 participants were able to complete a submaximal fitness test at a median of 12 days post-stroke. One minor adverse event was recorded. Of the 21 participants unable to complete the fitness test; 4 declined to complete the test, 9 were unable to commence the test, and 8 were unable to complete the first stage of the protocol due to stroke-related impairments. Participants with mild stroke, greater motor and cognitive function, and fewer depressive symptoms were more likely to be able to complete the cardiorespiratory fitness test. Cardiorespiratory fitness testing was safe for most people with mild-to-moderately severe ischemic stroke and transient ischemic attack in the early subacute phase, but only two-thirds of the participants could complete the test.

A Comparison of Substrate Utilization Profiles During Maximal and Submaximal Exercise Tests in Athletes.

BackgroundExercise is primarily sustained by energy derived from lipids (plasma free fatty acids and intramuscular triglycerides), and glucose (plasma glucose and muscle glycogen). Substrate utilization is the pattern by which these fuel sources are used during activity. There are many factors that influence substrate utilization. We aim to delineate the effect of exercise intensity and body composition on substrate utilization.ObjectiveThe objective of our study was to discern the differences in substrate utilization profiles during a maximal and submaximal graded exercise test, and to determine the extent to which body composition influences substrate utilization during the exercise tests.MethodsA total of 27 male athletes, 32.5 ± 11 years of age, were recruited for this study. Body composition was analyzed using a bioelectrical impedance analyzer. Maximal and submaximal exercise tests were performed on a treadmill. A novel graded submaximal treadmill protocol was used for the submaximal test.ResultsAverage percent body fat (PBF) was 15.8 ± 5%. Average maximal oxygen consumption (VO2max) was 47.6 ± 9 mL/kg/min, while the average exercise intensity (percent VO2max) at which participants were shifting to glucose predominance for energy during the maximal and submaximal tests were 76 ± 8.3% and 58.4 ± 21.1%, respectively. A paired-samples t-test was conducted to compare percent VO2max at crossover point in maximal and submaximal graded exercise tests. There was a significant difference in percent VO2max at the crossover point for maximal (76 ± 8.3%) and submaximal (58 ± 21.1%) tests (t = 4.752, p = 0.001). A linear regression was performed to elucidate the interaction between exercise intensity at the crossover point and body composition during a maximal and submaximal graded exercise test. There was a significant effect of PBF on percent VO2max at crossover point during the maximal graded exercise test [F(1,24) = 9.10, P = 0.006] with an R2 of 0.245. However, there was no significant effect of PBF on percent VO2max at crossover point during the submaximal graded exercise test (P > 0.05).ConclusionSubstrate utilization, represented by the crossover point, is dependent on the rate of increase in exercise intensity. At maximal efforts, the crossover to carbohydrates from fats as the predominant fuel source occurs at a significantly later stage of percent VO2max than at submaximal efforts. Furthermore, body composition represented by PBF is a significant predictor of substrate utilization during maximal efforts. Athletes with a relatively higher PBF are more likely to have increased lipid oxidation during high intensity exercises than those with a lower body fat percentage.